LOCAL SEISMIC AND HYDRAULIC EFFECTS CAUSED BY TOHOKU (M=9) EARTHQUAKE IN GEORGIA

Abstract

Presently, there are a lot of observations on the significant impact of such small external forcing’s on the seismic regime, namely on the seismicity induced by wave trains of remote strong earthquakes, tides, reservoir exploitation, big explosions, magnetic storms, strong electrical pulses, etc. Many of such results still are subject of intense scientific discussions, but nevertheless are quite logical in the light of undisputable strong nonlinearity of processes underlying seismicity. One of main factors reducing local strength is the pore pressure of fluids, which is the scope of relatively new direction, so called hydroseismology. The stresses imparted by teleseismic wave trains according to assessments are 105 times smaller than confining stresses at the depth, where the tremors are generated due to a nonlinear effect of super-sensitivity to a weak impact. According to publications, the majority of dynamically triggered events were observed in regions of extensional tectonics and high hydrothermal activity. At the same time some evidence of dynamic triggering from great Tohoku (M=9) earthquake has been obtained recently in the West Caucasus, which is a continental collision zone. Besides tremors, clear identical anomalies in water levels at passing S- and Love-Rayleigh teleseismic waves on the large part of territory of Georgia from Borjomi to Kobuleti has been observed. Their relation to seismic tremors is investigated.